sname = "学习python使我快乐"
print("sname[:]",sname[:])
print("sname[3：8]",sname[3:8])
print("sname[:8]",sname[:8])
print("sname[3:]",sname[3:])
print("sname[3:8:2]",sname[3:8:2])
print("sname[:-4]",sname[:-4])
print("sname[:-8:-3:2]",sname[-8:-3:2])
print("sname[8:3:-2]",sname[8:3:-2])